Method of imparting water repellency to materials and product thereof



June 19, 1962 '5 WATER ABSORPTION T. RAPHAEL ErAL 3,039,894

METHOD OF IMPARTING WATER REPELLENCY TO MATERIALS AND PRODUCT THEREOF Filed Jan. 22, 1959 FOR MALDEHYDE CONDENSED WITH PHENOLS SUBSTITUTED IN PARA POSITION WITH I. OCTYL 2.NONYL 3.DODECYL 4.BENZYL 5. CYGLOHEXYL L RESIN BASED ON FIBER WEIGHT FIG. I

INVENTORS THOMAS RAPHAEL LAURENCE R. B. HERVEY ATTORNEY United States Patent 3,039,894 METHOD OF IMPARTING WATER REPELLENCY T0 MATERIALS AND PRODUCT THEREOF Thomas Raphael, Winchester, and Laurence R. B. Hervey, West Concord, Mass., assignors to Arthur D. Little, Inc, Cambridge, Mass, a corporation of Massachusetts Filed Jan. 22, 1959, Ser. No. 788,369 3 Claims. (Cl. 117-1355) This invention relates to a process for imparting water repellent qualities to materials and more particularly to making various fabrics, whether made from natural or synthetic fibers, water repellent.

In many applications and uses it is desirable, if not necessary, to make fabrics water repellent. For example, certain types of clothing; protective canvases, tarpaulins, and the like; and items such as tents must be treated to repel water. A number of methods have been developed in the past to render specific fibers and the articles and fabrics made therefrom water repellent. Among these methods which have been used may be cited treating the fabric with waxes and oils, vulcanizing natural rubber in them, impregnating with synthetic resins such as polyvinyl chloroacetate, cellulose acetate and the like, and treating with other materials such as thermosetting silicone resins and methylol stearamide. Some of these treatments are adversely affected by changes in temperature, while others are subject to oxidation and subsequent embrittlement. In some cases the treatment has added undue weight to the item treated, while others have been only temporary, being easily removed in laundering and/or dry cleaning.

It would therefore be desirable to have a treating agent and a method of applying it which could be used to impart water repellent qualifies to fibers and fabrics either of natural or synthetic origin.

It is therefore an object of this invention to provide a treating agent in which fibers and fabrics may be immersed or coated to render them water-repellent. It is another object to provide such a treating agent which is applicable to a wide variety of fibers and fabrics whether they are of natural or synthetic origin. It is yet another object toprovide such treating agents, which when introduced into fabrics to render them water repellent, will not deprive the fabrics of their original characteristics as fabrics. These and other objects will become apparent in the following discussion.

The invention will be described in detail below and with reference to the drawings in which FIG. 1 is a plot showing the relationship between the percents of certain treating agents used and their effectiveness in rendering paper water repellent.

Fibers and fabrics are waterproofed in accordance with this invention by treating the fiber and fabric with a condensation resin formed by condensing a substituted phenol and a source of formaldehyde under certain specified conditions to form a condensation product which is soluble in acetone. After an adequate quantity of the resin has been deposited on the fiber or fabric the resin is cured to give a material which is flexible, and which retains essentially all of its original properties while at the same time exhibiting a marked increase in water repellency.

In a co-pending application, Serial No. 788,368, filed January 22, 1959, there is disclosed the use of condensation resins, formed when substituted phenols are reacted with a formaldehyde source, made up into a solution conice taining a strongly alkaline material and added in this solution to cellulosic paper-making stock.

The phenolic compound suitable for forming the condensation resin used in treating fibers and fabrics to render them water repellent is a difunctional phenolic structure and the substituent group may be in the ortho or para position. The substituent may be a saturated or unsaturated aliphatic radical having from 6 to 12 carbon atoms; or it may be a saturated or unsaturated cyclic radical as long as it does not result in the formation of a compound having conjugated unsaturation throughout its structure.

The number of substituent groups on the phenol is limited to one. If two radicals, as defined above, are present as substituents on the phenolic structure, the condensation reaction product required in the practice of this invention cannot be formed under the conditions specified. Even if substituted phenols outside those defined above could be reacted under more drastic conditions the resulting resin would be very diflicult to cure on fibers and fabrics.

With regard to the cyclic substituents, it appears that if the resulting substituted phenol has conjugated unsaturation throughout (such as would result for example in the use of para-phenyl-phenol) there would occur active groups on the substituent which would interfere with the condensation reaction.

The substituted phenol may then generally be defined as a phenol having a substituent radical so placed that not more than two methylol groups supplied by the formaldehyde source may add to the phenolic structure. The substituent radical is selected from the group consisting of saturated and unsaturated aliphatic radicals having from 6 to 12 carbon atoms and saturated and unsaturated cyclic hydrocarbon radicals which when joined to the phenolic ring do not result in the formation of a compound having conjugated unsaturation throughout.

The source of formaldehyde may include formaldehyde, paraformaldehyde, trioxymethylene, hexamethylenetetramine, or any other compound which will readily liberate formaldehyde at temperatures under about 200 F. It has been found that the higher aldehydes such as butyraldehyde and acetaldehyde are not practical reactants for this condensation reaction since the reaction does not proceed at any reasonable rate at the temperatures preferably employed.

In forming a condensation resin suitable for imparting Water repellent properties to fibrous materials in accordance with this invention it is necessary to form a condensation resin which will, unlike normal phenol-formaldehyde resins, permit the materials to remain flexible. Therefore, the choice of the substituted phenol used in forming the condensation resin is important and to be distinguished from the phenol normally used in forming phenol-formaldehyde resins and from a mixture of substituted phenols and substantial amounts of unsubstituted phenols.

By substantial amounts of unsubstituted phenols is meant these quantities which will materially effect the physical characteristics of the material. Limiting the quantity of unsubstituted phenols does not, of course, preclude the incorporation of additives such as resins, fillers, dyes, pigments, sizes and the like which are incorporated into the treated material for reasons other than making them water repellent. The scope of this invention includes the incorporation of such additives.

In condensing substituted phenols with formaldehyde a methylol phenol is formed by adding one or two CH OH groups to the substituted phenol in ortho and/ or para positions (the meta position will not react with formaldehyde). The possible di-functional substituted phenols may be represented as on on X R X X I X R where R is the substituent radical as defined above and X represents the possible positions where the methylol groups from the formaldehyde source may attach.

In forming the condensation resin the molar ratio of formaldehyde to substituted phenol may vary from about two mols of formaldehyde to one mol of substituted phenol to about one to one.

The condensation product which is used to imp-art water repellency to fabrics in accordance with the practice of this invention is prepared prior to its incorporation onto the fibers or fabrics. The product is generally a viscous material and condensation is preferably carried out under moderate conditions of temperature and for periods which result in a resin which remains soluble in the lower alcohols and in acetone.

Moderate temperature conditions in the process of this invention may be further defined as ranging from about 150 to 200 F. Condensation reactions carried out at room temperature do not give as satisfactory condensation products (with respect to their ability to impart water repelling characteristics) as those carried out within the range specified. It is important that the final condensation resin to be used be soluble in acetone, for if it is carried out to the point Where it is no longer soluble in acetone the resulting resin is not suitable for the treatment of fabrics to obtain the results desired.

In general the condensation product is formed by mixing the substituted phenol, the source of formaldehyde, a suitable catalyst and one of the lower alcohols, along with some water, if desired. This mixture is then refluxed for a period ranging from about one half to ten hours and at a temperature preferably below about 200 F, but above about 150 F. The temperature and time may be varied within these limits as long as the resulting condensation product remains soluble in acetone.

In the formation of the condensation product either an acidic or basic catalyst may be used. For example, it has been found equally acceptable to use strong bases such as sodium hydroxide, a milder base such as calcium hydroxide, or even a strong acid such as hydrochloric. This wide choice of catalyst is apparently due to the nature of the linkages formed in the condensation reaction, i.e., few, if any cross-linkages are formed. Although it would probably be possible to achieve the required condensation reaction without a catalyst, the catalyst is preferable if the reaction is to take place in a reasonable length of time in the required temperature range.

The condensation product resulting from the reaction of this invention may be handled in one of two Ways. After the product has been formed it may be washed with Water and then redissolved in a suitable solvent (acetone or the lower alcohols) prior to its introduction onto the fibers or fabrics. It is also possible, however, to use the reaction product as it is formed since it is in solution and it may not be necessary to wash it and redissolve it, thus saving the cost of additional steps and also of replacing the solvent. The form in which the resin is used will depend upon whether or not the fabric or fibers made water repellent can tolerate the strongly alkaline nature of the reaction solution. Of course, the solution may be neutralized before use, but this tends to lower the water tolerance of the resin and care must be taken not to precipitate it out.

The condensation resin is preferably introduced into the fiber or fabric by making it up into a solution using either acetone or one of the lower alcohols along with some water as a solvent. The water may be present in an amount which is just less than that quantity which will precipitate the resin. The concentration of the condensation resin in the solvent should range between about 10 to 35% by weight of resin solids. The fiber or fabric to be treated is then immersed in the solution, or the solution may be applied as a coating on at least one surface. Known coating techniques including spraying, roller-coating and the like are satisfactory for this purpose.

The amount of resin taken up by the fibers or fabric will vary depending upon the manner in which the resin solution is applied and upon the degree of water repellency desired. This amount may range from about 1% by fabric weight when the solution is coated on the surface to as much as about 50% when the fabric or fibers are immersed for an extended period of time in the solution. For general purposes the preferred range is from about one to about 10 percent resin solids, based on the fabric or fiber weight.

After the condensation resin has been applied to the fiber or fabric the treated material is then dried to expel the solvent and the resin is cured, conveniently at a temperature ranging between about 275 and about 400 F.

The resulting treated fiber or fabric is flexible and exhibits a marked increase in ability to repel water.

This invention may be further described in the following examples which are meant to be illustrative, not limiting.

EXAMPLE I 120 grams of nonyl phenol 22.8 grams of NaOH (96%), 45 grams of formalin (37% formaldehyde), 300 grams of water and 100 grams of isopropyl alcohol were mixed with moderate stirring. The mixture was heated in a vessel equipped with a condenser and refluxing in this vessel was carried out for 6 hours at 188 F.

At the end of the condensation reaction and after the mixture had cooled, it was neutralized with acetic acid to a pH of 6 and washed to give a viscous liquid. This condensation product was then dissolved in isopropyl alcohol to give a concentration of 25 percent by weight. A sample of rag paper was then immersed in this resin solution for approximately one-half hour, a time which permitted good penetration of the solution into the paper. The treated paper was then dried and cured in an oven at 300 F. for about one hour. The resin pickup by the paper amounted to about 5 percent by weight.

The treated paper was then evaluated for its ability to repel Water and was given a rating of good. The water repellency was measured by dropping water on the fabric. If the drop rolled off, it was rated as good, if it was gradually absorbed it was rated poor, and if it was absorbed immediately, it was rated as having no water repellency.

In this example, the molar ratio of formaldehyde to substituted phenol was 1:1. Additional resins using nonyl phenol and formalin having molar ratios of 1.521 and 2:1 were made up. The condensation resin was formed in the same manner, dissolved in isopropyl alcohol, and used to treat paper as described above. The performance of the resulting treated paper was essentially the same as that when the molar ratio was 1:1.

The amount of sodium hydrom'de catalyst used in this example will be seen to be equivalent to one mol catalyst for each mol of substituted phenol. Experimentation has indicated that other basic catalysts may be substituted for the sodium hydroxide and that the amount of catalyst may be reduced to an equivalent of about 0.05 mol for each mol of substituted phenol. Likewise,

Water Repelleizcy of Fabrics Treated With a Condensm tion Resin Formed by Reacting NOiZyl Phenol With Formalin Percent Treated Resin Untreated Water Re- Fabric Added Water Repellency (based on pellency (drop test) fiber wt.)

Cotton 50 good. Wool 57 good. Orlon (acrylic fiber)" 28 good. Acrilan (acrylic fiber). 15 good. Arnel (cellulose ester) 28 good. Nylon (polyamide fib 55 good.

It will be seen that treated cotton fabric exhibited essentially the same performance as paper, since both are of cellulosic origin and both normally absorb large quantities of water. A marked improvement in the degree of water repellency will be noted.

EYAMPLE HI Condensation resins using octyl-phenol, nonyl-phenol, dodecyl-phenol, cyclohexyl-phenol and benzyl-phenol as the substituted resins and formalin (37% formaldehyde) as the formaldehyde source were prepared as in Example I. The ratio of available formaldehyde to substituted phenol was about 1:1 and sodium hydrox de amounting to about one-half mol per mol of substituted phenol was used as a catalyst during the condensation reactions.

The resins thus formed were washed thoroughly with water and each was redissolved in a mixture of equal weights of isopropyl alcohol and water. The resin 'con tent of these solutions ranged from between 20 and 30 percent by weight.

A series of strips of a high-density rag paper were immersed in each of these solutions to obtain a range of resin pickups. The strips were then dried to remove substantially all of the solvent, calendered and cured at about 300 F. The water absorption of each of these strips was then determined by immersing the strip in water at 70 F. for four hours, removing them and measuring the amount of water absorbed. The results are plotted in FIG. 1, wherein curves for the five different condensation resins are drawn to show the relation between the amount of resin pickup and the amount of water absorbed. Since decreasing water absorption i the result of rendering a cellulosic material water repellent, the data plotted in H6. 1 show the marked efiect on water repellency of even a very small amount of the resin of this invention.

The resin treatment of this invention is eiiective in increasing the water repellency of both natural and synthetic fibers, the latter including acetates, polyarnides, acrylics and polyesters. Moreover, the treated fibers and fabrics remain flexible and retain substantially an of their original characteristics.

We claim:

1. Method of rendering an article formed from fibers water repellent, characterized by treating said article with a solution of a condensation resin, said resin being the reaction product of a formaldehyde source with a substituted phenol condensed in the presence of a lower monohydric alcohol as a reaction medium under refluxing conditions at a temperature below about 200 F., said condensation resin being characterized as soluble in acetone, said substituted phenol having a substituent radical so placed that at least one but not more than two methylol radicals of said formaldehyde source can add to said substituted phenol, said substituent radical being selected from the group consisting of saturated and unsaturated aliphatic radicals having a total of between 6 and 12 carbon atoms and saturated and unsaturated cyclic hydrocarbon groups which when joined to the phenolic ring do not result in the formation of a compound having conjugated unsaturation throughout, said solution of said resin consisting essentially of from about 15 to about 35% resin solids dissolved in a mixture of a lower alcohol and water as a solvent, the quantity of said water in said mixture being less than that which will precipitate said resin, removing substantially all of said solvent from the resulting treated article, and curing said resin absorbed by said fibers at temperatures ranging from about 275 to about 400 F.

2. Method of claim 1 wherein said treating step comprises immersing said article in said solution whereby the condensation resin is absorbed by said fibers.

3. Method of claim 1 wherein said treating step comprises coating at least one surface of said article with said solution.

References Cited in the file of this patent UNITED STATES PATENTS 2,582,239 Dodd Jan. 15, 1952 

1. METHOD OF RENDERING AN ARTICLE FORMED FROM FIBRES WATER REPELLENT, CHARACTERIZED BY TREATING SAID ARTICLE WITH A SOLUTION OF A CONDENSATION RESIN, SAID RESIN BEING THE REACTION PRODUCT OF A FORMALDEHYDE SOURCE WITH A SUBSTITUTED PHENOL CONDENSED IN THE PRESENCE OF A LOWER MONOHYDRIC ALCOHOL AS A REACTION MEDIUM UNDER REFLUXING CONDITIONS AT A TEMPERATURE BELOW ABOUT 200*F., SAID CONDENSATION RESIN BEING CHARACTERIZED AS SOLUBLE IN ACETONE, SAID SUBSTITUTED PHENOL HAVING A SUBSTITUENT RADICALS SO PLACED THAT AT LEAST ONE BUT NOT MORE THAN TWO METHYLOL RADICALS OF SAID FORMALDEHYDE SOURCE CAN ADD TO SAID SUBSTITUTED PHENOL, SAID SUBSTITUENT RADICAL BEING SELECTED FROM THE GROUP CONSISTING OF SATURATED AND UNSATURATED ALIPHATIC RADICALS HAVING A TOTAL OF BETWEEN 6 AND 12 CARBON ATOMS AND SATURATED AND UNSATURATED CYCLIC HYDROCARBONN GROUPS WHICH WHEN JOINED TO THE PHENOLIC RING DO NOT RESULT IN THE FORMATION OF A COMPOUND HAVING CONJUGATED UNSATURATED THROUGHOUT, SAID SOLUTION OF SAID RESIN CONSISTING ESSENTIALLY OF FROM ABOUT 